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Chapter 2 Functional Description GEH-6632 EX2100 User’s Guide
Auto Reference – AUTO REF
The AUTOREF block generates an auto (or Auto Control (AC)) setpoint for the
Automatic Voltage Regulator (AVR) based on user-supplied parameters and
conditions. Raise/lower inputs to AUTO REF come in from the other devices on the
Data Highway such as the turbine control or HMI. A variable rate integrator
generates the output setpoint within preset limits. The setpoint is combined with
other auxiliary stabilizing and protective signals in the EXASP block to form the
reference to the AVR block.
AVR Setpoint – EXASP
The EXASP block combines a number of functions to produce the setpoint
(reference input) to the AVR, and the AVR tracking value. The EXASP inputs are as
follows:
• Stabilizing signal from the PSS block
• Output from the AUTOREF block
• External test signal
• Protective signal generated by the UEL block
• Reactive current input (feedback)
• Voltage magnitude input (feedback)
• Frequency input (feedback)
The outputs to the AVR block are the AVR setpoint and tracking value.
Automatic Voltage Regulator – AVR
Generator terminal voltage is
controlled by the AVR.
The AVR block maintains the generator terminal voltage. The setpoint (reference)
comes from the EXASP block, and the feedback is the generator voltage. The error
value is input to a proportional plus integral (PI) regulator with integrator windup
protection, which produces an output signal. Figure 2-12 shows the block diagram.
When the AVR is enabled, the AVR output is passed through directly from the track
input to the output of the Field Voltage Regulator (FVR).